JPH10278772A - Tandem type negative pressure booster - Google Patents

Abstract

PROBLEM TO BE SOLVED: To smooth inflow of atmospheric air from the third port to the first port so as to improve responsiveness and so as to reduce generation of collision noise maximally by tilting a front side inside wall face of the third port inside wall face so that it is brought closer to the front side toward the radius directional outside of a piston boss. SOLUTION: The third port 231 is arranged in a valve cylinder part 10b front end part in a piston boss 10. In the inside wall face of the third port 231 , the front side inside wall face 23a1 on the front side is tilted so that it is gradually brought close to the front side toward the radius directional outside of the piston boss 10. The atmospheric air flowing into the first port 21 from the third port 231 is guided by means of the front side inside wall face 23a1 and introduced smoothly so as to quickly flow into a front part working chamber without any delay, so that improvement of responsiveness can be accomplished. On the other hand, a collision angle is reduced and generation of collision noise can be suppressed maximally even when the atmospheric air from the third port 231 collides against the rear end opening part in the first port 21.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tandem type negative pressure booster used for operating a brake master cylinder of an automobile, and more particularly to a boss portion slidably supported on a partition plate and a boss portion. A piston boss made of synthetic resin is constituted by a valve cylinder portion integrally provided at the rear end, and a front portion and a rear booster piston are commonly connected to the boss portion,
A first port connecting between the front and rear working chambers, a second port connecting between the front and rear negative pressure chambers, and extending in a radial direction of the valve cylinder at a position corresponding to a rear end opening of the first port. And a third port communicating with the rear working chamber is provided in the piston boss, and a control valve for switching the third port to the second port and the atmosphere and communicating therewith is provided in the valve cylinder.

[0002]

2. Description of the Related Art Such a tandem type negative pressure booster is already known, for example, as disclosed in Japanese Utility Model Laid-Open No. 4-129362.

[0003]

However, in the prior art, as shown in FIG. 6, the rear end of the first port 21 extends along the axial direction of the piston boss 10 and the boss portion 10a of the piston boss 10 extends. And the valve body 10
A third port 23 'extending in the radial direction of b is provided at the front end of the valve cylinder portion 10b with a constant cross-sectional area, so that the control valve 24 allows the third port 23' to communicate with the atmosphere. When activated, the inflow of air from the third port 23 'to the rear working chamber 4b is smooth, but the front working chamber (not shown) has the first port 2' from the third port 23 '.
Since the flow direction is changed to 1 at a right angle, the inflow of the air is not smooth, and therefore, the inflow of the air into the front working chamber is delayed, and it is hard to say that the response is excellent. Also, the atmosphere from the third port 23 '
The collision sound generated by colliding with the rear end opening at a right angle is inevitable.

[0004] The present invention has been made in view of such circumstances, and smoothes the inflow of air from the third port to the first port to improve responsiveness and minimize the generation of collision noise. It is an object of the present invention to provide a tandem type negative pressure booster.

[0005]

In order to achieve the above object, an invention according to claim 1 includes a boss portion slidably supported by a partition plate that partitions the inside of a booster shell into a front and a rear shell chamber. A piston boss made of synthetic resin is constituted by a valve cylinder portion slidably supported on a rear wall of the booster shell and integrally connected to a rear end of the boss portion, and a front shell chamber is formed on the front side. A front booster piston that partitions the front negative pressure chamber and the rear front working chamber and a rear booster piston that partitions the rear shell chamber into the front rear negative pressure chamber and the rear working chamber are common to the boss portion. A first port connecting between the front and rear working chambers, a second port connecting between the front and rear negative pressure chambers, and a valve cylinder portion at a position corresponding to the rear end opening of the first port. Third port extending radially to the rear working chamber But it provided in the piston boss,
In a tandem-type negative pressure booster in which a control valve for switching the third port to the second port and communicating with the atmosphere is provided in the valve cylinder portion, the front inner wall surface located on the front side among the inner wall surfaces of the third port is as described above. The piston boss is formed so as to be inclined so as to be located on the front side as it goes outward in the radial direction of the piston boss.

According to such a configuration, when the control valve is brought into a state in which the third port communicates with the atmosphere, the air from the third port is smoothly supplied to the rear working chamber as it is,
In addition, since the front inner wall surface of the third port is inclined so as to be located on the front side toward the outside along the radial direction of the valve cylinder, the atmosphere is smoothly guided from the third port to the first port. Accordingly, it is possible to avoid a delay in the inflow of the atmosphere into the front working chamber, to improve the response, and to provide the rear end opening from the third port to the first port. It is possible to reduce the collision angle of the atmosphere with the air to minimize the generation of collision sound.

According to a second aspect of the present invention, in addition to the configuration of the first aspect, the rear end surface of the boss portion is formed as a flat surface along a plane perpendicular to the axis of the boss portion. A first port is provided on the boss portion with a rear end opening to the rear end surface, the valve cylinder portion projects rearward from the rear end surface, and the third port is an outer end of a front inner wall surface thereof. Is provided on the valve cylinder portion so as to substantially coincide with the rear end opening edge of the first port, so that the third port can be formed by the core when the piston boss is molded, and the formation of the third port Becomes easier.

According to a third aspect of the present invention, in addition to the configuration of the first aspect, the third port is formed such that the outer end of the front inner wall surface is closer to the rear end opening edge of the first port. Is also provided in the piston boss in the front, so that the inflow of air from the third port to the first port becomes smoother, the responsiveness can be further improved, and the generation of collision noise Can be suppressed more effectively.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described based on embodiments of the present invention shown in the accompanying drawings.

FIGS. 1 to 3 show a first embodiment of the present invention. FIG. 1 is a longitudinal side view of a tandem type negative pressure booster, and FIG. 2 is a state in which a third port is connected to the atmosphere. FIG. 3 is an enlarged view of a main part of FIG. 1, and FIG. 3 is a sectional view showing a die structure for forming a piston boss.

First, in FIG. 1, a cylinder body 2 of a master cylinder M for brake operated by the booster B is mounted on a front surface of a booster shell 1 of the tandem type negative pressure booster B.

The booster shell 1 has a pair of front and rear shell halves 1a and 1b connecting opposite ends to each other, and is sandwiched between the two shell halves 1a and 1b so that the inside of the booster shell 1 is connected to the front shell chamber 3. A partition plate 1c for partitioning the rear shell chamber 4 is provided, and the rear shell half 1b is supported by a support portion S such as a vehicle body.

The front shell chamber 3 includes a front booster piston 5 housed in the shell chamber 3 so as to be able to reciprocate back and forth, a front shell half 1a and a partition wall which are bonded and bonded to the rear surface of the piston 5. The front diaphragm 6 sandwiched between the plates 1c divides into a front front negative pressure chamber 3a on the front side and a rear front working chamber 3b on the rear side. The rear shell chamber 4 includes a rear booster piston 7 housed in the shell chamber 4 so as to be able to reciprocate back and forth, and both shell halves 1a, 1b together with a partition plate 1c.
A rear diaphragm 8, which is fixed between the rear booster piston 7 and bonded to the rear surface of the rear booster piston 7, is divided into a front rear negative pressure chamber 4a and a rear rear working chamber 4b.

The front and rear booster pistons 5 and 7 are each formed in a ring shape from a steel plate, and these booster pistons 5 and 7 are slidably supported by a partition plate 1c via a seal member 9 in a boss portion 10a. Are attached to the front end and the rear end, respectively. The rear end face 1 of the boss 10a
6 is formed on a flat surface along a plane orthogonal to the axial direction of the boss 10a, and the rear end face 16 of the boss 10a
, A front end portion of a valve cylinder portion 10b constituting the piston boss 10 together with the boss portion 10a is coaxially and integrally connected,
The valve cylinder portion 10b is provided on a rear extension cylinder 17 projecting from the rear wall of the booster shell 1 and covering the valve cylinder portion 10b.
Is slidably supported via the.

The piston boss 10 composed of the boss portion 10a and the valve cylinder portion 10b is formed of a synthetic resin. The boss portion 10a has a large-diameter recess 11 having a circular cross section opened at the front end thereof and a front portion. And a small-diameter concave portion 13 having a circular cross-section and formed between the large-diameter concave portion 11 and the annular step portion 12 facing the base plate.
, And the return spring 15 is contracted between the front shell half 1a. Due to the spring force of the return spring 15, the piston boss 1
Therefore, both booster pistons 5 and 7 are always biased in the retreating direction. The retreat limit of both booster pistons 5 and 7 is such that a large number of raised protrusions (not shown) are provided on the rear surface of rear diaphragm 8 at the rear wall of booster shell 1. Is regulated by contact with

The front negative pressure chamber 3a is connected to a negative pressure source (not shown) (for example, the inside of an intake manifold of an internal combustion engine) via a negative pressure introducing pipe 19. The front working chamber 3b and the rear working chamber 4b are provided on the boss 10a such that at least a rear end thereof extends along the axial direction of the boss 10a and a rear end is opened to the rear end face 16 of the boss 10a. The front negative pressure chamber 3a and the rear negative pressure chamber 4a communicate with each other via a first port 21, and communicate with the inside of the valve cylinder 10b via a second port 22 provided in the boss 10a.
Further, the first port 21 is provided at the front end of the valve cylinder portion 10b.
At a position corresponding to the third position along the radial direction of the valve cylinder portion 10b.
Port 23 ₁ is provided. This third port 23 ₁
The control valve 24 provided in the valve barrel portion 10b alternately switches the communication between the second port 22 and the air introduction port 25 opened in the end wall 17a of the rear extension cylinder 17.

2, a control valve 24 including a valve element 31, a valve spring 34, a first valve seat 29 and a second valve seat 30, and a brake pedal are provided in the valve cylinder portion 10b. An input rod 27 connected to the input lever 26 is provided.

A valve piston 28 is slidably fitted to the boss 10a, and a front end of an input rod 27 passing through the air inlet 25 is swingably connected to the center of the valve piston 28. Is done.

The first valve seat 29 is formed in an annular shape and protrudes from the inner peripheral surface of the valve cylinder portion 10b. An annular second valve seat 30 surrounded by the first valve seat 29 is located behind the valve piston 28. A rubber valve body 3 formed on the end face and cooperating with these valve seats 29, 30
1 is disposed in the valve barrel portion 10b. The valve body 31 has a cylindrical shape with both front and rear ends open, and the rear end of the valve body 31 is formed by a holding cylinder 32 fitted on the inner peripheral surface of the valve cylinder section 10b. It is held in close contact with the inner peripheral surface.

The valve element 31 has a thin flexible portion 31a bent radially inward from the rear end thereof, and a thick valve portion 31b connected to the front end of the flexible portion 31a.
Is arranged to face the first and second valve seats 29 and 30. The valve portion 31b can be moved back and forth by deformation of the flexible portion 31a, and the first and second valve seats 29,
At the time of retreat, it is received at the front end of the holding cylinder 32.

An annular reinforcing plate 33 is embedded in the valve portion 31b, and a valve portion 31 is provided between the reinforcing plate 33 and the input rod 27.
A valve spring 34 for urging the valve b toward both valve seats 29 and 30 is contracted.

[0022] On the inner surface of the valve cylindrical portion 10b, the rear end of the outside of the first valve seat 29 and the second port 22 is opened, the inside in the third inner end of the port 23 ₁ of the first valve seat 29 It is opened. The inside of the second valve seat 30 includes a valve element 31 and a holding cylinder 3.
2 communicates with the air inlet 25 through the hollow portion.

Between the input rod 27 and the holding cylinder 32, a return spring 35 for urging the input rod 27 toward its rearmost position is contracted. The retreat limit of the input rod 27 is regulated by the stopper plate 36 screwed to the input rod 27 so as to be able to advance and retreat, abutting on the inner surface of the end wall 17 a of the rear extension cylinder 17. Therefore, when the stopper plate 36 is turned, the screwing position between the stopper plate 36 and the input rod 27 changes, so that the retreat limit of the input rod 27 can be adjusted back and forth. Fixing of the stopper plate 36 after this adjustment is performed by tightening a lock nut 37 which is also screwed to the input rod 27. The stopper plate 36
Is configured so that the stopper plate 36 does not block the air inlet 25.

An air filter 39 for filtering air taken into the valve cylinder 10b from the air inlet 25 is mounted on the valve cylinder 10b around the input rod 27. The air filter 39 has appropriate flexibility so as not to hinder the relative displacement between the input rod 27 and the valve cylinder 10b.

The boss portion 10a of the piston boss 10 is integrally provided with a cylindrical projection 40 coaxially projecting into the small-diameter concave portion 12 opened at the center of the front surface of the boss portion 10a.
The front end of the valve piston 28 slidably fitted in the cylindrical protrusion 40 is disposed in the cylindrical projection 40. The cylindrical projection 40 includes the output rod 4.
2 is slidably fitted to a fitting cylinder portion 42a provided integrally with the rear end of the cylinder 2. The elasticity opposed to the valve piston 28 is provided between the tip of the cylindrical projection 40 and the fitting cylinder portion 42a. The piston 43 is pinched. Moreover, the output rod 42 is
The through-hole 44 provided in the through hole 44 prevents the fitting cylinder portion 42a from being pulled out of the cylindrical projection 40 by the engagement of the seat plate 14 with the fitting cylinder portion 42a at the periphery of the through hole 44. Is done. The output rod 42 is connected to a piston 45 of the brake master cylinder M.

Although the configuration up to this point is not fundamentally different from the conventional one, according to the present invention, as shown in FIG. 2, the piston boss 10 is provided at the front end of the valve cylinder 10b at the front end. those 3 front side inner wall 23a ₁ located on the front side of the inner wall surfaces constituting the port 23 ₁ is formed to be inclined so as to be positioned on the front side as directed radially outwardly of the piston boss 10 There, moreover the front side in the outer end of the wall 23a ₁ is arranged substantially to coincide with the rear end opening edge of the first port 21.

In molding the piston boss 10 made of a synthetic resin, as shown in FIG. 3, a mold 4 corresponding to the outer shapes of the boss 10a and the valve cylinder 10b is formed.
6, boss portion 10a, and the mold 47 corresponding to the inner surface shape of the Bento portion 10b, the core 48 for forming at least a rear end portion of the first port 21, and a core for forming the third port 23 ₁ Although 49 and the like than are used, together with the rear end face 16 of the boss portion 10a is a flat surface along a plane perpendicular to the axis of the boss portion 10a, the third port 23 ₁ is the front side inner wall 23a _1, the piston The boss 10 is formed so as to be inclined so as to be located on the front side as it goes outward in the radial direction of the boss 10, and the outer end of the front inner wall surface 23 a ₁ is made substantially coincident with the rear end opening edge of the first port 21. With this arrangement, the core 49 can be moved in the radial direction of the piston boss 10 through the guide hole 50 provided in the core 48.

Next, the operation of the first embodiment will be described. First, in the rest state of the negative pressure booster B, as shown in FIG. 1, the input rod 27 is located at the retreat limit, and the control valve 24 causes the valve portion 31b to be seated on the first and second valve seats 29, 30. The front working chamber 3b and the rear working chamber 4b are connected to both negative pressure chambers 3a,
4a and the air introduction port 25 are in a neutral state in which they are not communicated with each other.
The negative pressure of the negative pressure source supplied through is stored, and the working chambers 3b and 4b hold the negative pressure appropriately diluted with the atmosphere. As a result, the front and rear booster pistons 5, 7 are provided with the front negative pressure chamber 3a and the front working chamber 3b.
In the meantime, a slight forward force is given due to the pressure difference generated between the rear negative pressure chamber 4a and the rear working chamber 4b, but these forward forces and the resilient force of the return spring 15 are balanced, and both booster pistons 5, 7 is stopped when it has advanced slightly from the retreat limit.

When the brake pedal 26 is depressed, the input rod 27 is depressed.
When the valve piston 28 is advanced, the booster pistons 5 and 7 are initially immobile, so that the second valve seat 30 is immediately separated from the valve portion 31b, and the working chambers 3b and 4b communicate with the atmosphere inlet 25. will be, as a result, together with the air that has flowed into the valve body 31 from the air inlet 25 passes through the second valve seat 30, is quickly introduced to the rear working chamber 4b through the third port 23 _1, 3rd port 23 ₁ to 1st
Since it is introduced into the front working chamber 3b through the port 21 and the working chambers 3b and 4b are made higher in pressure than the negative pressure chambers 3a and 4a,
The two booster pistons 5, 7 move forward against the force of the return spring 15 by obtaining a large forward force based on the pressure difference therebetween, and drive the piston 45 of the master cylinder M for braking forward via the output rod 42. . In this manner, the brake master cylinder M can be actuated in response to the depression of the brake pedal 26 to apply braking to the vehicle.

By the way, the front-side inner wall surface 23a ₁ of the third port 23 _1, because it is formed as an inclined surface inclined to the front side toward the radially outer valve cylinder portion 10b, a third port 23 ₁ The air flowing into the first port 21 from the first port 21 is guided by the front inner wall surface 23a ₁
1, the air can flow into the front working chamber 3b promptly without delay, and the responsiveness can be improved. The air from the third port 23 ₁ is even collides with the rear end opening of the first port 21, it is possible to suppress the generation of impact noise by reducing the impact angle of the air as much as possible.

The further third port 23 _1, by its front side in the outer end of the wall 23a ₁ and substantially coincide with the rear end opening edge of the first port 21 is intended to be provided to the valve cylinder portion 10b, the piston during molding of the boss 10, as shown in FIG. 3, the third port 23 ₁ can be formed in core 49, the third port 23 ₁ of the formation is facilitated.

FIGS. 4 and 5 show a second embodiment of the present invention. FIG. 4 is a sectional view of an essential part corresponding to FIG.
FIG. 3 is a cross-sectional view showing a mold structure for forming a piston boss.

The front side inner wall 23a ₂ located on the front side of the inner wall surfaces constituting the third port 23 _2, the piston boss 1
It is formed to be inclined so as to be located on the front side as it goes outward in the radial direction of 0. Moreover the outer end of the front side inner wall 23a _2, the third port 23 ₂ is the piston boss 10 so as to be disposed forwardly of the rear end opening edge of the first port 21
Is provided.

At the time of molding the piston boss 10, the boss 10a and the valve cylinder 10 are formed as shown in FIG.
b, a mold 47 'corresponding to the inner shape of the boss 10a and the valve cylinder 10b, a core 48' for forming at least the rear end of the first port 21,
And core 49 for forming the third port 23 ₂ '
Is used, but the rear end face 16 of the boss 10a is used.
Along with that there is the outer end of the front side inner wall 23a ₂ forward from, the core 49 'is, as a possible movement in the direction toward and away from the front side inner wall 23a _2, the core 48' in It is fitted in the provided guide hole 50 '. After completion Thus to molded, but the portion indicated by a chain line in the third port 23 ₂ A of FIG 5 remain unformed, so that post-processing is performed for part of the unformed.

According to the second embodiment, the third port 23
The outer end of the front side inner wall 23a ₂ in the ₂ first port 2
By being disposed on the front side of the rear edge of the rear opening,
It becomes possible to further smooth the flow of air from the third port 23 ₂ to the first port 21, thereby it is possible to further improve the responsiveness, suppress the generation of impact noise more effectively Can be.

Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above embodiments, and various design changes can be made without departing from the present invention described in the appended claims. It is possible to do.

[0037]

As described above, according to the first aspect of the present invention, the front inner wall surface of the third port is inclined so as to be located on the front side toward the outside along the radial direction of the valve cylinder. As a result, the air can be smoothly guided from the third port to the first port, and the air can quickly flow into the front working chamber to improve the responsiveness. The collision angle of the atmosphere from the three ports to the rear end opening of the first port can be reduced to minimize the generation of collision noise.

According to the second aspect of the present invention, the third port is provided in the valve cylinder portion such that the outer end of the front inner wall surface substantially coincides with the rear end opening edge of the first port. Thus, the third port can be formed by the core when the piston boss is molded, and the formation of the third port can be facilitated.

Further, according to the third aspect of the present invention, the third
The outer end of the front inner wall surface of the port is disposed forward of the rear end opening edge of the first port, so that the inflow of air from the third port to the first port is further smoothed, and the responsiveness is improved. It is possible to further improve, and it is possible to more effectively suppress the generation of the collision sound.

[Brief description of the drawings]

FIG. 1 is a vertical side view of a tandem type negative pressure booster according to a first embodiment.

FIG. 2 is an enlarged view of a main part of FIG. 1 in a state where a third port is communicated with the atmosphere.

FIG. 3 is a cross-sectional view showing a mold structure for forming a piston boss.

FIG. 4 is a sectional view of an essential part corresponding to FIG. 2 of a second embodiment.

FIG. 5 is a cross-sectional view showing a mold structure for forming a piston boss.

FIG. 6 is a sectional view corresponding to FIG. 2 of the prior art.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Booster shell 1c ... Partition board 3 ... Front shell chamber 3a ... Front negative pressure chamber 3b ... Front working chamber 4 ... Rear shell chamber 4a ... Rear negative Pressure chamber 4b Rear working chamber 5 Front booster piston 7 Rear booster piston 10 Piston boss 10a Boss part 10b Valve cylinder part 16 Boss part Rear end face 21 First port 22 Second port 23 ₁ , 23 ₂ Third port 23 a ₁ , 23 a ₂ Front inner wall surface 24 Control valve B Tandem Type negative pressure booster

Claims (3)

[Claims] 1. A boss (10a) slidably supported by a partition plate (1c) partitioning the inside of a booster shell (1) into front and rear shell chambers (3, 4), and the booster shell (1). ) Is slidably supported by a rear wall of the boss portion (1).
0a) and a valve cylinder portion (10b) integrally connected to the rear end, a piston boss (10) made of synthetic resin is formed, and the front shell chamber (3) is connected to the front front negative pressure chamber (3a). ) And a front booster piston (5) partitioning a rear front working chamber (3b), and a rear shell chamber (4) into a front rear negative pressure chamber (4).
a) and a rear booster piston (7) partitioning the rear working chamber (4b) on the rear side are commonly connected to the boss (10a), and a first connecting the front and rear working chambers (3b, 4b). Port (21) and front and rear negative pressure chambers (3
a, 4a) and a valve cylinder (1) at a position corresponding to the rear end opening of the first port (21).
Rear working chamber radially extending 0a) (third port leading to 4b) (23 _1, 23 ₂₎ is provided in the piston boss (10), a third port (23 _1, 23 ₂₎ in tandem vacuum booster provided in the second port (22) and a control valve which communicates with switching to the atmosphere (24) the valve cylinder portion (10a), a third port (23 _1, 2
3 ₂ ) The inner wall surface on the front side (23)
a _1, 23a ₂₎ is a tandem type vacuum booster, characterized in that it is formed to be inclined so as to be positioned on the front side as directed radially outwardly of the piston boss (10). 2. A rear end surface (16) of the boss (10a).
Is formed as a flat surface along a plane orthogonal to the axis of the boss (10a), and a first port (21) is provided in the boss (10a) with its rear end opened to the rear end surface (16). the valve cylinder portion (10b) is protruded backward from the rear end face (16), said third port (23 ₁₎ is the first port (21) the outer end of the front side inner wall surface (23a ₁₎
The tandem-type negative pressure booster according to claim 1, wherein the tandem type negative pressure booster is provided on the valve cylinder portion (10b) so as to substantially coincide with a rear end opening edge. 3. The piston boss (3), wherein the third port (23 ₂ ) is arranged such that the outer end of the front inner wall surface (23a ₂ ) is located forward of the rear end opening edge of the first port (21). 1
The tandem-type negative pressure booster according to claim 1, wherein the booster is provided in (0).